The present invention relates to a supporting structure that supports wheels of a vehicle to be freely rotatable in relation to the vehicle body.
Wheels of an automobile are supported freely retractably in relation to the vehicle body by a supporting structure that uses bearings. A heavy vehicle such as a truck requires it to bear radial loads and moment loads in order to support the vehicle body tereof. On the other hand, in the case of an automobile designed with emphasis on the maneuverability on off-road ground or a rough road such as snow-covered road, such as four-wheel drive vehicle, for example, excessive bending moments may be exerted on the wheels as the vehicle runs over bumps or depressions, thus causing an impact load in the radial direction on the bearings. Thus such vehicles often employ tapered roller bearings that have high impact resistance, as the bearings for the wheel supporting structure. In the prior art, it has been common to use a plurality of (for example, two) tapered roller bearings, that are separate from a hub, for each wheel, the bearings being assembled on an axle while being separated from each other in the axial direction.
However, the conventional configuration requires it to assemble the two tapered roller bearings individually on an axle, separately from the hub. Also the conventional configuration includes a large number of parts and requires such operations as the adjustment of the bearing clearance for applying a preload to the bearing during assembly onto the axle. Consequently, there has been a limitation to the reduction of assembly cost and material cost of the parts. For four-wheel drive vehicles which are required to have high maneuverability on rough ground, especially those of compact sizes, there is a need for higher degree of freedom in design of the wheel-related components, in order to make the wheel-related section more compact and improve the ride comfort and suspension performance. Thus there is a demand for a wheel supporting structure capable of supporting radial loads and moment loads, that are equivalent to or greater than those borne by two tapered roller bearings installed separately, while being light in weight, small in size, low in cost and high in impact resistance. An object of the present invention is to provide a low cost wheel supporting structure that eliminates the needs for the adjustment of the bearing clearance during assembly onto the axle, thereby improving the workability of assembling the support structure, and is light in weight, small in size and high in impact resistance.